Phil McKenzie said measures had since been put in place to ensure that a similar situation did not occur.

An inquest into the death of 15-year-old Rene Levi heard from Mr McKenzie and from the senior physical education teacher on that day, Tim Jolly, who admitted that he did not actually see Rene get out of the river when he was supervising the swimmers.

Four grade 9 classes went to Bells Parade on November 16, 2009, where they were given the option of swimming in the Mersey River or participating in land- based activities.

Rene was one of four boys out of between 60 and 80 students who went swimming. Mr Jolly said he indicated to them an area that they were permitted to swim in and told them to remain within his sight.

Rain set in around midday and students gathered under trees near the river before returning to school when it eased, the inquest heard.

Mr Jolly said the four students were told to get out of the water.

"My last recollection of Rene is him in the middle of the river, two or three metres from the bank," he said.

"I've thought long and hard about that and I've got nothing else."

Mr Jolly said two students told the teachers that Rene had gotten out of the water and headed back to school.

There was no roll-call or head count and the four teachers and one student teacher at the scene agreed it could be described as chaotic.

Hours later, during a kayaking lesson that Mr Jolly took after lunch, another student said Rene had not been seen during the break.

"I paddled down on my own to where the wooden seat is (where they'd been swimming)," Mr Jolly said.

"I didn't find anything and felt a bit better."

But at the end of the lesson, three boys told Mr Jolly that Rene had pretended to drown and was swimming under the water, then popping up and surprising other students.

That was when the teacher became quite worried and paddled down on his kayak again, past where he had gone the last time.

He found Rene's body under the water.

"It looked like a mannequin at first. It was hard to comprehend what I was looking at," he said.

Mr McKenzie told the inquest that protocols had changed since the tragic event.

Parents just used to tick a box on their children's enrolment forms to allow them to go on minor excursions like that one, but there was nothing to specifically give permission for swimming. They are now asked to sign an aquatic form in addition to other forms.

The inquest was told it was now standard that a roll-call would always be conducted and everyone would be accounted for before leaving an excursion.

The inquest was adjourned to December 21.